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Sow

Sow[e]
specifies that e should be collected by the nearest enclosing Reap.
Sow
specifies that e should be collected by the nearest enclosing Reap whose pattern matches tag.
Sow
specifies that e should be collected once for each pattern that matches a .
MORE INFORMATION
  • Sow returns e.
  • By having several identical , a single expression can be made to appear multiple times in a list returned by Reap.
  • Sow sows an expression with tag {tag}.
EXAMPLESCLOSE ALL
Basic Examples   (4)
Evaluate a sequence of expressions, "sowing" some to be collected by Reap:
Compute a sum, "sowing" at each step:
Make separate lists for expressions "sown" with different tags:
Reap only expressions "sown" with tag :
Evaluate a sequence of expressions, "sowing" some to be collected by Reap:
In[1]:=
Click for copyable input
Out[1]=
 
Compute a sum, "sowing" at each step:
In[1]:=
Click for copyable input
Out[1]=
 
Make separate lists for expressions "sown" with different tags:
In[1]:=
Click for copyable input
Out[1]=
 
Reap only expressions "sown" with tag :
In[1]:=
Click for copyable input
Out[1]=
Scope   (5)
Sow can be used anywhere in a computation:
It still works inside a function:
A single expression can be "sown" with multiple tags:
If a single tag is repeated, the expression is sown repeatedly:
A pattern in Reap can be used to specify which tags to collect:
The default is the pattern , so that everything is collected:
Tags can have any form; here they are True and False:
Applications   (3)
Make a list of all the steps taken in evaluating FindRoot:
Evaluate an iterated map, keeping iterates that are below 1/100:
Find equivalence classes with respect to the value of mod 10:
Properties & Relations   (2)
Sow[x] returns x, "sowing" it as a side effect:
Expressions sown are reaped by the innermost enclosing Reap:
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